Oscillatory fluid-pressure-operable machines

ABSTRACT

A vane-type oscillatory fluid-pressure-operable machine includes a cylindrical casing and a shaft extending therefrom, the fixed and movable vanes of the machine forming at least two variablevolume chambers. Sealing devices of a resilient material are carried upon the vanes at those faces thereof in slidable engagement with adjacent portions of the machine. A substantially rigid sealing ring is provided which is mounted upon and sealingly engages the shaft adjacent an end wall of the casing and which is engaged by the sealing devices so that it is urged axially thereby to be maintained in complete peripheral sealing engagement with said end wall whatever the rotational position of the shaft and movable vane or vanes with respect to the casing.

United States Patent Hyde [S4] OSCILLATORY FLUID-PRESSURE- OPERABLE MACHINES [72] Inventor: John Michael Hyde, Tuffley, En-

gland Assignee: Dowty Hydraulic Units Limited,

Cheltenham, England [22] Filed: Dec. 3, 1970 [Zl] App]. No.: 94,791

[56] References Cited UNITED STATES PATENTS 2/ l 966 Kummerman .92/1 22 2,550,180 4/ 1951 Allen, Jr ..92/ l 22 2,047,806 7/1936 Swanson et al ..277/ 169 FOREIGN PATENTS OR APPLICATIONS 964,684 7/ 1964 Great Britain ..277/l69 US] 3,682,050 Aug. 8, 1972 Primary Exandner-Martin P. Schwadron Assistant Examiner-Ronald H. Lazarus AttorneyYoung & Thompson ABSTRACT A vane-type oscillatory fluid-pressure-operable machine includes a cylindrical casing and a shaft extending therefrom, the fixed and movable vanes of the machine forming at least two variable-volume chambers. Sealing devices of a resilient material are carried upon the vanes at those faces thereof in slidable engagement with adjacent portions of the machine, A substantially rigid sealing ring is provided which is mounted upon and sealingly engages the shaft adjacent an end wall of the casing and which is engaged by the sealing devices so that it is urged axially thereby to be maintained in complete peripheral sealing engagement with said end wall whatever the rotational position of the shaft and movable vane or vanes with respect to the casing.

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SHEEI 1 OF 2 vr lllllillI IN VE N TOR Jaw/v Mama 66 05 I 'O M (AI mm vs OSCILLATORY FLUID-PRESSURE-OPERABLE MACHINES This invention relates to oscillatory fluid-pressureoperable machines.

According to this invention an oscillator fluid-pressure-operable machine includes a substantially cylindrical casing, a shaft extending at least towards the exterior of the casing through a bore in an end wall of the casing, at least one fixed vane formed with or carried by said casing and at least one movable vane formed with or carried by said shaft thereby to font: at least two variable-volume fluid chambers within the machine, sealing devices of a resilient material carried upon said vanes at those faces thereof which are slidable with respect to adjacent portions of the machine, and a substantially rigid sealing ring, which is mounted upon and sealingly engages said shaft adjacent said end wall and which is engaged by the sealing devices so that it is urged axially, thereby to be maintained in complete peripheral sealing engagement with said end wall whatever the rotational position of the shaft and movable vane or vanes with respect to the casing.

Preferably there is a small radial clearance between the shaft and the sealing ring to enable transverse relative movement to occur between them under the higher fluid pressure acting upon that portion of the sealing ring which is exposed to the chamber at higher pressure, thus to afford engagement and fluid sealing between the sealing ring and the shaft in the zone of that higher pressure chamber.

In this case it may be arranged that the clearance between the shaft and that portion of the sealing ring which is exposed to the chamber at lower pressure is open to that chamber to at least assist in providing a route for fluid from that chamber to the clearance between said shaft and said bore for lubrication of said shaft.

The sealing ring may be provided with an annular recess around its periphery on that face thereof adjacent said end wall, which recess is open to said clearance exposed to the chamber at lower pressure, whereby said fluid for lubrication is conductable completely around said shaft so as to reach the zone between said shaft and bore of maximum clearance, the position of that zone being dependent upon the direction of transverse fluid loading upon the shaft.

The sealing ring may be of metal and of part-circular cross-section, engaged at portions thereof by seatings of particular cross-section formed in said sealing devices.

Preferably also the shaft is partly supported by a further bore provided in the other end wall of the casing, and in this case two of said sealing rings are provided respectively in engagement with the two end walls.

The said resilient material may be rubber, or other rubber-like composition, having desired resilient characteristics.

The said machine may be an hydraulic actuator, or alternatively may be a fluid damper, or again a pump.

One embodiment of the invention will now be particularly described by way of example with reference to the accompanying diagrammatic drawings, of which:

FIG. 1 is an external side elevation of an hydraulic actuator,

FIG. 2 is an enlarged cross-section taken along the line ll ll on FIG. 1,

FIG. 3 is an enlarged cross-section taken along the line lll Ill on FIG. 2,

HO. 4 is an enlarged cross-section taken along the line lV IV on FlG. 2, and,

F IG. 5 is an explanatory view of part of P16. 2.

Referring to the drawings, an oscillatory hydraulically operable actuator 1 comprises three casing sections which are held together in unit assembly by set bolts 2 at one end portion of the actuator and by set bolts 3 at the other end portion of the actuator, certain of the set bolts, as at 4 and 5, having their heads received in milled-away portions as at 6 and 7 in the respective end casing section or cover member 8. This cover member is provided with a bearing bore 9. The center section or cylindrical casing 11 houses a shaft 12 of steel which as shown in FIG. 1 projects through the bearing bore 9 to the exterior where it is provided with splines 10 by which the shaft is connectible to a device to be operable by the actuator. The other end casing section or cover member 13 also has a bearing bore 14 through which the shaft 12 justs projects, the bearing bores 9 and 14 thus supporting the shaft for rotation.

The cylindrical casing 11 cover members 8 and 13 are of cast iron while the shaft 12 is of steel.

Suitable shaft sealing means (not shown) are provided in conventional manner in the bearing bores 9 and 14.

With reference more particularly to FIG. 2, the cylindrical casing 11 is provided with one radially inwardly directed fixed vane 15 bolted in convenient manner by set bolts (not shown) to the inner wall of the casing, while the shaft 12 carries one vane 16 which is movable therewith about the axis 17 of rotation of the shaft. These vanes, which extend substantially for the full axial length of the casing 11, are of cast iron. The radially inner end portion of the fixed vane 15 is in sliding engagement with the surface 18 of the shaft, while the outer end portion of the movable vane 16 is in slidable engagement with the cylindrical inner surface 19 of the casing 11. Both end faces of both vanes are in sliding engagement with the respective adjacent end cover members, and in conventional manner these vanes are each provided with grooves 20 and 21 housing resilient sealing devices in the form of strip-like members 22 and 23 of rubber which are backed up on either side in the respective groove by backing members 24, 25; 26, 27. These members are of urethane material filled with molybdenum disulphide. On the fixed vane these striplike members afford sealing between the vane end faces and the cover members and also between the vane inner end portion and the shaft, and on the movable vane they aflord sealing between the vane end faces and the cover members and also between the vane outer end portion and the surface 19 of the casing.

Thus, the vanes 15 and 16, the casing 11 and the end cover members define two variable-volume liquid chambers 28 and 29, ports 30 and 31 in the casing 11 providing means for introducing liquid under pressure to the chambers and exhausting liquid from the chambers. Such introduction and exhaust are effected by control valve means (not shown) arranged externally of the actuator.

As shown in FIG. 3, the rubber members 22 (and also 23) are provided with seatings, as at 32, of part-circular cross section and of arcuate form. These seatings are adjacent to the junction of the inner face 33 of each cover member and the shaft 12. As shown in FIG. 4 each vane is itself provided with a recess 34 of similar shape to the seating 32, but which is of larger radial dimension in cross-section. The members 24, 25; 26, 27 are also provided with recesses, as at 35, of similar shape and dimension. Mounted upon the shaft 12 with a diametral clearance of 0.00l inch are two substantially rigid sealing rings of steel, the one associated with the cover member 13 being shown at 36 but the one associated with the other cover member not being shown. Each of the rings 36 is pre-loaded against its respective seating 32 by the respective cover member, such preloading being afforded by the fact that although the ring is of a cross-sectional shape similar to that of the seating 32, it is of slightly larger cross-sectional area. Thus, when the respective cover member is bolted to the casing 11 there is interference between the ring and the rubber of the members 22/23. In this way although the ring is seated only at two portions thereof around its periphery, it is maintained on its face 37 in liquid seating engagement with the face 33 of the respective end cover member 13.

Each of the two seating rings 36 is provided with an annular recess 38 at the junction of the face 37 thereof and its circular face 39.

The shaft sealing function afforded by each of the rings 36 will now be described with particular reference to FIG. 5.

Considering the shaft 12 and movable vane 16 to be in the position as shown in FIGS. 2 and S with the chamber 28 subjected to liquid under high pressure (2,000 psi.) and the chamber 29 open to exhaust (but maintaining 100 p.s.i. therein), the effective center of hydraulic loading within the chamber 28 and upon the shaft 12 and vane 16 will be disposed such that the shaft 12 is urged to the right in FIG. against the righthand part of the bore 14. Also each ring 36 is urged to the right so that it takes up the 0.001 inch clearance with its left-hand portion sealing against the left-hand portion of the shaft. The diametral clearance between the shaft and bore 14 in this embodiment is 0.002 inch. Hence, a clearance space 40 of crescent-shaped crosssection will be formed between the left-hand part of the shaft and the bore 14. This crescent-shaped clearance which is shown somewhat exaggerated in FIG. 5 is in the high pressure zone of the actuator, and the sealing rings 36 at each end of the actuator bridge this clearance at the end faces 33 of the respective cover members 8 and 13 substantially to prevent leakage from the chamber 28 into the clearance.

It will be understood that with subsequent anticlockwise movement of the shaft 12 and vane 16 this crescent-shaped clearance will move in this direction also because the above-mentioned effective center of pressure is also moving, and in an anti-clockwise direction. However, the rings 36 are of such dimension that the sealing of the rings against the end faces 33 is maintained whatever the position of the shaft and movable vane, as is the case when the shaft and movable vane are subsequently caused to move in the clockwise direction upon instead pressurizing the chamber 29 and exhausting the chamber 28.

Thus, the pre-loaded support of the rings 36 in the seatings 32 is adequate for sealing against loss of high pressure liquid from the chamber 28 or 29, each ring being supported circumferentially in two places. Further, it will be understood that as well as holding the rings 36 in sealing engagement with the shaft in the high pressure zone 28 or 29, the high fluid pressure acting upon the sealing rings in this zone also assists in maintaining sealing of the rings against the end faces 33.

In addition to the above end face sealing function the rings 36 also serve to open a route from whichever of the chambers 28 and 29 is at low pressure to the shaft/ bore clearance for shaft lubrication purposes.

Assuming the chamber 29 to be open to exhaust and the chamber 28 to be pressurized with the vane 16 and shaft 12 moving in the anti-clockwise direction, as explained above the rings 36 are urged to the right in FIGS. 2 and 5 due to the liquid pressure in the chamber 28 acting upon them. Each ring 36 therefore produces a clearance space 41 of crescent-shaped cross-section to the right of the shaft as shown in FIG. 5. Liquid in the chamber 29 enters this crescent and thus also enters the annular recess 38. Thus, it passes around the recess and into the crescent-shaped clearance space 40 between the shaft 12 and the bore 14 to lubricate the shaft as it runs in the bore. Since both crescents 40 and 41 are moving around with the shaft and movable vane, good distribution of lubricating liquid is afforded. Such low pressure lubrication is isolated from the high pressure side of the actuator.

When the direction of rotation of the actuator is changed to clockwise, the low pressure liquid then in the chamber 28 is instead introduced to a clearance space of crescent-shaped cross-section to the left in FIG. 5 of the shaft 12, and in the converse way from that with anti-clockwise rotational movement, low pressure liquid finds it way through the annular recess 38 to a clearance space of crescent-shaped cross-section to the right of the shaft 12 and within each bore nine-fourteenths thus to lubricate the shaft as it runs in the bore.

It is of course very necessary for such low pressure lubrication of the shaft that the said clearances of crescent-shaped cross-section on the low pressure side of the sealing rings do not at any time extend beyond the vane sealing members to the high pressure side thereof, and thus to ensure this the sealing ring/shaft clearance must be carefully selected, bearing in mind the possible wear of the ring and slight ovality which may well occur after extended periods of use of the actuator.

Sealing rings (not shown) are provided around the shaft at the outer end portions of the bores to prevent escape of low pressure lubricating liquid to the exterior of the machine.

The invention is not limited to actuators as in other embodiments the rotary machine may be a fluid damper, or again a pump.

Further, the invention is not limited to machines having only one fixed vane and only one movable vane.

Although in the embodiment described with reference to the drawings the sealing rings are of steel, in other embodiments the sealing rings are of other metal or of such a hard plastics material as to afford the rings their substantially rigid characteristics.

The invention is not limited to the cross-sectional shape of the sealing rings above described with reference to the drawings, as in other embodiments the cross-section of the rings may be of other desirable and suitable shape. Further, the rings need not each be provided with an annular recess for conducting low pressure liquid around the shaft for lubrication as instead such recesses may be provided in end walls of the casing or in the shaft itself. Alternatively, no such recesses need be provided, the clearances of crescent-shaped cross-section between the rings and shaft themselves being then arranged so that they overlap the crescentshaped clearances between the shaft and the bores thus to be able to conduct the low pressure lubricating liquid to the latter clearances for shaft lubrication.

Although in the embodiment described with reference to the drawings the machine has two of said sealing rings for the shaft, one adjacent each end cover member, in other embodiments the machines may only have one such sealing ring, other sealing means being provided in association with the other end cover member.

Again, the invention is not limited to a machine having a casing comprising a cylindrical part and two end cover members, as instead alternative constructions may provide a casing with one end closure member formed integrally therewith, while at the other end of the casing a detachable end cover member is provided. Alternatively, a casing may be provided comprising two similar parts held together, each part having a respective end closure member formed integrally therewith.

Where the machine is an actuator, means may be provided within it to afford automatic retardation of the actuator as it approaches either end of its stroke, and/or means may be provided for preventing airspeed of the actuator under high applied external loads.

1 claim:

1. An oscillatory fluid-pressure-operable machine including a substantially cylindrical casing, a shaft extending at least towards the exterior of the casing through a bore in an end wall of the casing, at least one fixed vane formed with or carried by said casing and at least one movable vane formed with or carried by said shaft thereby to form at least two variable-volume fluid chambers within the machine, sealing devices of a resilient material carried upon said vanes at those faces thereof which are slidable with respect to adjacent portions of the machine, and a substantially rigid sealing ring, which is mounted upon and sealingly engages said shaft adjacent to said end wall and which is engaged by the sealing devices so that it is urged axially thereby to be maintained in positive axial sealing engagement with said end wall whatever the rotational position of the shaft with respect to the casing and, means defining a small radial clearance between the shaft and the sealing ring to enable transverse movement to occur between them under the higher fluid pressure acting upon that portion of the sealing ring which is exposed to the chamber at higher pressure, thus to afford engagement and fluid sealing between the sealing ring and the shaft in the zone of that chamber at higher pressure, the clearance between the shaft and that portion of the sealing ring which is exposed to the chamber at lower pressure being open to said chamber to at least assist in providing a route for fluid from said chamber to clearance formed between said shaft and said bore for lubrication of said shaft.

2. A machine as claimed in claim I, wherein the sealing ring is provided with an annular recess around its periphery on that face thereof adjacent said end wall, which recess is open to said clearance exposed to the chamber at lower pressure, whereby said fluid for lubrication is conductable completely around said shaft so as to reach the zone between said shaft and bore of maximum clearance, the position of that zone being dependent upon the direction of transverse fluid loading upon the shaft.

3. A machine as claimed in claim 1, wherein the sealing ring is of metal and of part-circular cross-section, engaged at portions thereof by seatings of part-circular cross-section formed in said sealing devices.

4. An oscillatory fluid-pressure-operable machine including a substantially cylindrical casing, a shah extending at least towards the exterior of the casing through a bore in an end wall of the casing, at least one fixed vane carried by said casing and at least one movable vane carried by said shaft, thereby to form at least two variable-volume fluid chambers within the machine, sealing devices of a resilient material carried upon said vanes at those faces thereof which are slidable with respect to adjacent portions of the machine, and a substantially rigid sealing ring which is mounted upon and sealingly engages said shaft adjacent to said end wall and which is engaged at circumferentially spaced portions thereof by those parts of said sealing devices adjacent thereto under a pre-load afforded by an interference relationship provided between the said portions of the sealing ring and said parts of said sealing devices so that the sealing ring is axially preloaded against said end wall, resultant support of the sealing ring in the axial direction by the sealing devices being solely through the intermediary of said parts where they engage said circumferentially spaced portions, said sealing ring thereby being maintained in positive axial engagement with said end wall whatever the rotational position of the shaft with respect to the casing.

5. A machine as claimed in claim 4, wherein it is arranged that clearance between the shaft and that portion of the sealing ring which is exposed to the chamber at lower pressure is open to that chamber to at least assist in providing a route for fluid from that chamber to clearance formed between said shaft and said bore for lubrication of said shaft.

6. A machine as claimed in claim 4, wherein the shaft is partly supported by a further bore provided in the other end wall of the casing, two of said sealing rings being provided respectively in engagement with the two end walls.

7. A machine as claimed in claim 4, and comprising an hydraulic actuator.

8. A machine as claimed in claim 4, wherein the rigid sealing ring is of metal and said resilient material is rubber.

9. A machine as claimed in claim 4, wherein the sealing ring is of part-circular cross-section, the said portions thereof engaging, with said interference relationship, seatings of part-circular cross-section formed in said parts of said sealing devices.

10. A machine as claimed in claim 9, wherein each respective vane face adjacent to said end wall has whilst the sealing ring has said interference relationship with said sealing devices, a substantial clearance is provided between the sealing ring and the respective vane itself. 

1. An oscillatory fluid-pressure-operable machine including a substantially cylindrical casing, a shaft extending at least towards the exterior of the casing through a bore in an end wall of the casing, at least one fixed vane formed with or carried by said casing and at least one movable vane formed with or carried by said shaft thereby to form at least two variable-volume fluid chambers within the machine, sealing devices of a resilient material carried upon said vanes at those faces thereof which are slidable with respect to adjacent portions of the machine, and a substantially rigid sealing ring, which is mounted upon and sealingly engages said shaft adjacent to said end wall and which is engaged by the sealing devices so that it is urged axially thereby to be maintained in positive axial sealing engagement with said end wall whatever the rotational position of the shaft with respect to the casing and, means defining a small radial clearance between the shaft and the sealing ring to enable transverse movement to occur between them under the higher fluid pressure acting upon that portion of the sealing ring which is exposed to the chamber at higher pressure, thus to afford engagement and fluid sealing between the sealing ring and the shaft in the zone of that chamber at higher pressure, the clearance between the shaft and that portion of the sealing ring which is exposed to the chamber at lower pressure being open to said chamber to at least assist in providing a route for fluid from said chamber to clearance formed between said shaft and said bore for lubrication of said shaft.
 2. A machine as claimed in claim 1, wherein the sealing ring is provided with an annular recess around its periphery on that face thereof adjacent said end wall, which recess is open to said clearance exposed to the chamber at lower pressure, whereby said fluid for lubrication is conductable completely around said shaft so as to reach the zone between said shaft and bore of maximum clearance, the position of that zone being dependent upon the direction of transverse fluid loading upon the shaft.
 3. A machine as claimed in claim 1, wherein the sealing ring is of metal and of part-circular cross-section, engaged at portions thereof by seatings of part-circular cross-section formed in said sealing devices.
 4. An oscillatory fluid-pressure-operable machine including a substantially cylindrical casing, a shaft extending at least towards the exterior of the casing through a bore in an end wall of the casing, at least one fixed vane carried by said casing and at least one movable vane carried by said shaft, thereby to form at least two variable-volume fluid chambers within the machine, sealing devices of a resilient material carried upon said vanes at those faces thereof which are slidable with respect to adjacent portions of the machine, and a substantially rigid sealing ring which is mounted upon and sealingly engages said shaft adjacent to said end wall and which is engaged at circumferentially spaced portions thereof by those parts of said sealing devices adjacent thereto under a pre-load afforded by an interference relationship provided between the said portions of the sealing ring and said parts of said sealing devices so that the sealing ring is axially preloaded against said end wall, resultant support of the sealing ring in the axial direction by the sealing devices being solely through the intermediary of said parts where they engage said circumferentially spaced portions, said sealing ring thereby being maintained in positive axial engagement with said end wall whatever the rotAtional position of the shaft with respect to the casing.
 5. A machine as claimed in claim 4, wherein it is arranged that clearance between the shaft and that portion of the sealing ring which is exposed to the chamber at lower pressure is open to that chamber to at least assist in providing a route for fluid from that chamber to clearance formed between said shaft and said bore for lubrication of said shaft.
 6. A machine as claimed in claim 4, wherein the shaft is partly supported by a further bore provided in the other end wall of the casing, two of said sealing rings being provided respectively in engagement with the two end walls.
 7. A machine as claimed in claim 4, and comprising an hydraulic actuator.
 8. A machine as claimed in claim 4, wherein the rigid sealing ring is of metal and said resilient material is rubber.
 9. A machine as claimed in claim 4, wherein the sealing ring is of part-circular cross-section, the said portions thereof engaging, with said interference relationship, seatings of part-circular cross-section formed in said parts of said sealing devices.
 10. A machine as claimed in claim 9, wherein each respective vane face adjacent to said end wall has recesses which are disposed adjacent and alongside the respective seating in each said sealing device to receive adjacent portions of said sealing ring, and which are of a part-circular cross-sectional shape of larger radius than that of the seatings of the sealing devices whereby, whilst the sealing ring has said interference relationship with said sealing devices, a substantial clearance is provided between the sealing ring and the respective vane itself. 